This invention relates to a magnetic tape traveling system of a magnetic recording and reproducing apparatus, and, more particularly, to a guide roller having a shape and configuration for enabling adjustments of the tape traveling system to be effected in a simplified manner at the time of assembly.
In a video tape recorder for household use, for example, the present practice requires bringing of a magnetic tape obliquely into contact with a tape guide of the cylindrical shape having a rotary head. Guide pins and guide rollers are used in this type of magnetic tape traveling system. In the prior art, as shown in FIG. 1 a guide roller 9 comprises a shaft 1, a roller 2 and flanges 3 and 4 located at the top and the bottom of the roller 2, respectively. The guide roller 9 is as shown in FIGS. 2a, 2b, used, for example, in a cassette type video tape recorder for guiding, in cooperation with a tilting pin 10 (10'), a magnetic tape 8 to bring same into contact with a cylinder 11 having a rotary head with a predetermined tilt for a predetermined circumferential extent. More specifically, the tilting guide pins 10 and 10' twist the magnetic tape 8 to bring same into contact with the cylinder 11 which is tilted with respect to a chassis surface 31, to cause the tape 8 to move spirally along the peripheral surface of the cylinder 11. The guide rollers 9 and 9' have the function of changing the direction of travel of the magnetic tape 8.
In FIG. 2a, the numeral 5 designates a two-reel tape cassette in which two reels 6 and 6' are located in the same plane, with guide pins 7 and 7' being attached to the tape cassette 5. The numeral 12 designates a fixed head for recording and reproducing a sound signal and control signal. A capstan 13 and a pinch roller 15 are concerned in the travel of the magnetic tape 8 in a recording mode or a playback mode.
The roller 2 of the guide rollers 9 and 9' of the prior art of the tape traveling system has the function of changing the path of travel of the magnetic tape 8. Since the inner peripheral surface and the outer peripheral surface of the roller 2 are coaxial cylindrical surfaces, the roller 2 itself is unable to exert a force on the tape 8 in a direction parallel to the longitudinal axis of the roller 2. Thus, the flanges 3 and 4 have the function of regulating the movement of the tape 8 along the axial length thereof. The flanges 3 and 4 are spaced apart from each other a distance which is slightly greater than the width of the tape 8, to avoid damage to the tape 8. Thus in order to regulate the position of the tape 8 along the axial length of the roller 2 and the pressing of the tape 8 against the upper flange 3 or the lower flange 4, it has been common practice to push up or down the tape 8 by slightly tilting the shaft 1 of the roller 2 in such a manner that no curling of the tape occurs near the inlet and outlet of the flanges 3 and 4 or the edges of the tape 8 do not strike hard the edges of the flanges 3, 4.
The operation of adjusting the relative positions of the guide roller 9 and the magnetic tape 8 is troublesome and time consuming because the angle at which the shaft 1 is tilted is very small or in the range between 20.degree. and 40.degree.. Moreover, when the direction of travel of the tape 8 is reversed for switching the recorder to a playback mode, the force exerted on the tape 8 by the roller 2 has its direction reversed, with a result that the position of the tape 8 with respect to the axial length of the roller 2 undergoes changes and a reproduced picture of high quality is unobtainable.
In addition, tilting of the shaft 1 would cause the edges of the tape 8 to readily strike the edges of the flanges 3 and 4, so that the tape 8 would tend to curl in the vicinity of the guide rollers 9, 9'.